Thanks, Jim. "Own goal" apparently is idiomatic, I can't recall hearing it used here in the States. We use the term goal in basketball, and field goal in American football, but the logistics of those games are such that it would be virtually impossible to score against your own team, hence no need for the phrase "own goal".

There have been some cases where someone ran the wrong way with a football and scored a touchdown for the opponents. It's pretty rare, though, and usually is BIG news when it happens.